Display screen or portion thereof with a graphical user interface



FIG. 1 is a perspective view of a display screen or portion thereof with a graphical user interface in accordance with the present invention, shown in a first embodiment on a tablet;

FIG. 2 is a front view thereof;

FIG. 3 is a perspective view of a display screen or portion thereof with a graphical user interface in accordance with the present invention, shown in a second embodiment on a monitor; and,

FIG. 4 is a front view thereof.

The broken line showing of a tablet in FIGS. 1, 2 and of a monitor in FIGS. 3, 4 illustrates environment of the claim. The remainder of the broken lines illustrate portions of the display screen with graphical user interface. The broken lines form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with a graphical user interface, as shown and described. 